Liquid crystal display device

ABSTRACT

A liquid crystal display device, by which a reduction of costs of a color filter is realized and declining of the transmittance or reflectance due to an alignment error is suppressed, comprising a pair of substrates arranged facing to each other over a liquid crystal layer, wherein one substrate is formed pixels PXL arranged in matrix. Each pixel is formed a reflection portion for reflecting an outside light and a transmission portion for transmitting a light. The other substrate is formed a color filter colored to be different colors (red, green and blue) corresponding to respective pixels. One or more color adjusting windows CFW having a coloring concentration of zero or less than that of other portions are provided on reflection regions CFR superposing with reflection portions inside pixel regions corresponding to respective pixels.

The subject matter of application Ser. No. 10/471,372 is incorporatedherein by reference. The present application is a continuation of U.S.Ser. No. 10/471,372, filed Sep. 9, 2003, now U.S Pat. No. 7,148,938,which is a U.S. National Stage of PCT Application No. PCT/JP03/00482,filed Jan. 21, 2003, which claims priority to Japanese PatentApplication No. JP 2002-013611 filed Jan. 23, 2002, all of whichapplications are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an active matrix type liquid crystaldisplay device, particularly relates to a so-called hybrid type liquidcrystal display device wherein both of a reflection portion and atransmission portion exist in each pixel, furthermore specificallyrelates to a configuration of a color filter able to be applied to bothof the reflection portion and the transmission portion.

BACKGOUND ART

A hybrid type liquid crystal display device is disclosed, for example,in the Japanese Unexamined Patent Publication No. 11-52366 and theJapanese Unexamined Patent Publication No. 11-183892. A hybrid typeliquid crystal display device performs reflection type display by usingan outside light by reflecting the outside light irradiating from thefront surface side on a reflection layer on the back surface side when asufficiently bright outside light (natural light and room lighting,etc.) can be obtained, while when sufficient outside light cannot beobtained, it performs transmission type display by using a light of abacklight arranged on the back surface side of the liquid crystaldisplay device.

FIGS. 1A and 1B are schematic views of an example of a conventionalhybrid type liquid crystal display device. FIG. 1A shows theconfiguration of a section of one pixel.

As shown in the figures, the hybrid type liquid crystal display devicecomprises a pair of a first substrate 1 and a second substrate 2arranged facing to each other at the front and back. On the innersurface side of the first substrate 1 is formed a transparent commonelectrode 3, and on the inner surface side of the second substrate 2 isformed a pixel electrode 4. A pixel is formed at a part where the commonelectrode 3 formed on the first substrate 1 and respective pixelelectrodes 4 formed on the second substrate 2 face to each other. Bybeing matched with the pixel, a color filter CF is provided on the first(front side) substrate 1.

Below, the first substrate 1 provided with the color filter CF will bereferred to as a CF substrate in some cases in the presentspecification.

A liquid crystal layer 5 as an electric optical layer is held betweenthe pair of the first and second substrates 1 and 2 at the front andback. The liquid crystal layer 5 blocks/transmits an incident light foreach pixel in response to a voltage applied between the electrodes 3 and4.

The second (back side) substrate 2 is provided with a reflection layer6. The reflection layer 6 has an opening for every pixel and flatlydivides each pixel to a transmission portion T in the opening and areflection portion R outside the opening. In the present example, thereflection layer 6 is made of a metal film formed on a relief shapesurface of the substrate 2 and composes a part of the pixel electrode 4explained above. Also, the transmission portion T is formed atransparent conductive film, such as ITO, and the opening explainedabove is formed and composes a part of the pixel electrode 4.

As is clear from the above explanation, the pixel electrode 4 formed onthe second substrate 2 has the hybrid configuration of the metal filmprovided to the reflection portion R and the transparent conductive filmprovided on the transmission portion T. Such a pixel electrode 4 isdriven for every pixel by a switching element, for example, driven by athin film transistor (TFT).

The second substrate 2 being formed the TFT for driving pixels will bereferred to as a TFT substrate in some cases in the presentspecification below.

The color filter CF is separately configured for a reflection region CFRcorresponding to the reflection region R and a transmission region CFTcorresponding to the transmission region T by using different materials.As shown in the figure, a light transmits the color filter CF twice inthe reflection region CFR. On the other hand, a light transmits thecolor filter CF only once in the transmission region CFT.

Therefore, in order not to cause much difference in color tone betweenthe reflection portion R and the transmission portion T, a coloringconcentration of the reflection region CFR is made lower than that ofthe transmission region CFT in advance. For this reason, even a part ofa color filter CF colored to be an identical color in an identical pixelwas conventionally produced by separate processes by using differentmaterials in the reflection region CFR and the transmission region CFT.

FIG. 1B schematically illustrates a plane shape of a liquid crystaldisplay device shown in FIG. 1A. As shown in the figure, respectivepixels PXL are separated in lattice by a black mask BM. Each pixel PXLis flatly divided to a transmission portion T at the center and areflection portion R around it and has a so-called hybrid configuration.The color filter is patterned so as to approximately correspond to thepixels marked off by the black mask BM. Typically, pixel regions of thecolor filter corresponding to respective pixels PXL are colored to bethree primary colors, red, green and blue.

A hybrid type liquid crystal display device aims to always realize aneasy-to-watch display under any circumstances. Thus, it becomes areflection type display for displaying a screen by using a reflectionlight in the same way as a printed matter in a bright circumstance,while in a dark circumstance, it becomes a transmission type display byusing a backlight. To realize a color display by such a hybrid typedisplay, it is necessary to form a color filter adjusted to thetransmission type and a color filter adjusted to the reflection type onthe CF substrate side. Conventionally, a method of forming a colorfilter separately through a production process of a transmission type CFand a production process of a reflection type CF was general.

However, this method requires a longer production process and morematerials and kinds to be used. Therefore, there is a disadvantage thata color filter used in a hybrid type display becomes double inproduction costs comparing with a color filter used in a normaltransmission type display.

Also, when forming both of the transmission type color filter and thereflection type color filter in one pixel, there is a disadvantage thatthe transmittance or reflectance declines when an alignment error arisesbetween the two.

DISCLOSURE OF THE INVENTION

An object of the present invention is to reduce costs of a color filterby realizing a reduced process with less materials and to provide aliquid crystal display device comprising a color filter by whichdeclining of the transmittance or reflectance due to an alignment erroris not caused.

To attain the above object, a first aspect of the present invention is aliquid crystal display device characterized by comprising a pair offirst substrate and a second substrate arranged facing to each otherover a liquid crystal layer, the first substrate is formed pixelsarranged in matrix, and each pixel is formed a reflection portion toreflect an outside light and a transmission portion to transmit a light,and the second substrate is formed a color filter colored to bedifferent colors corresponding to respective pixels; wherein the devicecomprises one or more color adjusting windows having a coloringconcentration of zero or less than that of other portions are providedinside pixel regions corresponding to respective pixels and onreflection regions superposing with the reflection portions in the colorfilter.

Preferably, the color adjusting window is formed inside the reflectionregion leaving a distance of 2 μm or more from an edge of the reflectionregion. Also, the color filter comprises a plurality of color adjustingwindows in one pixel region, and respective windows are separated fromone another by 10 μm or more in the pixel region. Also, a plurality ofwindows are arranged for respective pixel regions of different colorsand arrangement directions of the plurality of windows are differentbetween the pixel regions of different colors in the color filter.Alternately, one window is arranged for respective pixel regions ofdifferent colors and an arrangement direction of the window is differentbetween the pixel regions of different colors in the color filter. Also,pixel regions of different colors are directly adjacent to each othernot over a black mask in the color filter.

Also, a second aspect of the present invention is a liquid crystaldisplay device characterized by comprising a pair of first substrate anda second substrate arranged facing to each other over a liquid crystallayer, the first substrate is formed pixels arranged in matrix, and eachpixel is formed a reflection portion to reflect an outside light and atransmission portion to transmit a light, and the second substrate isformed a color filter for coloring respective pixels to be differentcolors; wherein arrangement coordinates of the transmission portion in apixel is different between pixels colored to be different colors.

According to the present invention, a reflection region and atransmission region form a common color filter in basically separatepixel region. Because different materials and separate productionprocesses are not applied for the reflection region and transmissionregion as in the conventional method, a cost reduction can be attained.On the reflection region, one or more color adjusting windows having acoloring concentration of zero or less than that of other portions isformed. By providing the windows, there is not much difference in colortone between the reflection region and the transmission region. In otherwords, a color filter applied to the transmission type is formed alloverthe pixel region and windows are provided on a part of the reflectionregion based on a specific rule. Due to this, it optically functions asa color filter applied to the reflection type. Consequently, a two-waytype color filter can be produced at a low cost without using specialmaterials for a color filter applied to a reflection type and withoutperforming a production process of a reflection type color filter.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A and 1B are schematic views of an example of a conventionalhybrid type liquid crystal display device.

FIG. 2 is a plan view of a principle part of a liquid crystal displaydevice according to the present invention.

FIG. 3 is a flowchart of a production method of the liquid crystaldisplay device according to the present invention.

FIG. 4 is a schematic plan view of a conventional liquid crystal displaydevice.

FIG. 5 is a flowchart of a production method of a conventional liquidcrystal display device.

FIG. 6 is a graph of spectral transmittance of a conventionaltransmission CF.

FIG. 7 is a graph of spectral transmittance of a conventional reflectionCF.

FIG. 8 is a graph of spectral transmittance of a reflection CF accordingto the present invention.

FIG. 9 is a chromaticity diagram of the reflection CF according to thepresent invention.

FIGS. 10A to 10C are disassembled perspective views of the generalconfiguration of a hybrid type liquid crystal display device.

FIGS. 11A to 11C are schematic views of a specific example of a colorfilter according to the present invention.

FIGS. 12A and 12B are schematic views of a color filter according to areference example.

FIG. 13 is a disassembled perspective view of the configuration of ahybrid type liquid crystal display device according to the presentinvention.

FIG. 14 is a schematic view of a patterning method of a color filter.

FIGS. 15A and 15B are graphs of relative intensity distribution of anexposure light amount.

FIG. 16 is a schematic plan view of a specific example of a color filteraccording to the present invention.

FIG. 17 is a chromaticity diagram of the color filter shown in FIG. 16.

FIG. 18 is a schematic plan view of another embodiment of a liquidcrystal display device according to the present invention.

FIG. 19 is a plan view of a liquid crystal display device according tothe present invention and shows color windows CFW having lowered colorconcentrations formed by partial exposure in the process of FIG. 14.

BEST MODE FOR CARRYING OUT THE INVENTION

Below, preferred embodiments of the present invention will be explainedin detail with reference to the drawings.

FIG. 2 is a schematic plan view of a principle part of a liquid crystaldisplay device according to the present invention.

Generally, an active matrix type liquid crystal display device comprisesa pair of a first substrate (CF substrate) and a second substrate (TFTsubstrate) arranged facing to each other over a liquid crystal layer.The TFT substrate is formed pixels PXL arranged in matrix, and eachpixel is formed a reflection portion for reflecting an outside light anda transmission portion for transmitting a light. On the other hand, theCF substrate is formed a color filter colored to be different colorscorresponding to respective pixels PXL. In FIG. 2, pixels colored to bethree primary colors, red, green and blue, respectively are shown as aset to facilitate understanding. This color filter CF comprises areflection region CFR corresponding to the reflection portion and atransmission region CFT corresponding to the transmission portion insidethe pixel regions corresponding to the respective pixels PXL.

In the present embodiment, a common color filter is formed over both ofthe reflection region CFR and the transmission region CFT. Accordingly,there is no difference between the reflecting color filter CF and thetransmitting color filter CF in terms of materials. Instead, thereflection region CFR of the color filter CF is formed one or more coloradjusting windows CFW having a coloring concentration of zero or lessthan that of other portions. Basically, by forming the windows(hereinafter, also referred to as CF windows) on the color filterapplied to the transmission type, optical characteristics required to acolor filter CF of the reflection region CFR are realized.

Namely, an equivalent reflecting CF can be formed by providing thewindows without using materials for a reflection CF.

Generally, the minimum unit that can be identified by human eyes is 30μm square or so. By making the color adjusting CF windows as fine as 30μm or less, an existence of the CF windows become visually indistinctivebut able to adjust color tone of the color filter CF of the reflectionregion CFR.

Preferably, the color adjusting windows CFW are formed inside thereflection region CFR and away from the edges by 2 μm or more. Byarranging the windows CFW inside the pixel region, even when there is analignment error, the aperture ration of the windows is made constant bykeeping the windows not superposing with windows CFW of adjacent pixels.The aperture ration of the windows delicately affects color tone of thecolor filter, so that is has to be controlled at high accuracy. In thiscase, it is preferable to form the windows CFW inside the pixel regionby 2 μm or more considering an alignment error between pixels.

In the color filter according to the present embodiment, a plurality ofcolor adjusting windows CFW are included in one pixel region in somecases. In an example shown in FIG. 2, two CF windows are respectivelyprovided to red and green color filters. In this case, the CF windowsare preferably formed away from each other by 10 μm or more in the pixelregion. Generally, the CF windows can be formed by using aphotolithography technique. In this case, when considering resolution ofan exposure apparatus, etc., highly accurate CF windows can be formed byleaving a distance of 10 μm. When the CF windows get closer than that,it sometimes becomes difficult to separate the two in photolithography.

FIG. 3 is a flowchart of a production method of a CF substrate shown inFIG. 2.

First, a black mask for blocking a light is formed in a Black process(ST1). Next, a transmission CF portion (CFT) and a reflection CF portion(CFR) of a pixel to be colored red among the RGB trio are simultaneouslyexposed to form a red color filter (ST2). Then, in a green pixeladjacent to the red pixel, the transmission CF portion and thereflection CF portion are simultaneously exposed to form a green filter(ST3). Finally, in a blue pixel adjacent to the green pixel, thetransmission CF portion and the reflection CF portion are simultaneouslyexposed to form a blue color filter (ST4). In this case, at the time offorming color filters of the respective colors by exposure developmentprocessing, also CF windows can be opened at a time, so that therearises no burden in terms of processes.

FIG. 4 is an example of a conventional color filter. To facilitateunderstanding, the same reference numbers are used for portionscorresponding to the color filter of the present invention shown in FIG.2. In the conventional method, different color filter materials wereused for the transmission CF portion (CFT) and the reflection CF portion(CFR) in pixels of the respective colors. Generally, a material of theCFT has a higher coloring concentration than that of the CFR.

FIG. 5 is a flowchart of a production method of the color filter shownin FIG. 4. First, a black mask for blocking a light is formed in a Blackprocess (ST11). Next, a red color filter is formed only on atransmission CF portion as a part of a pixel (ST12). Then, a green colorfilter is formed on a transmission CF portion as a part of a green pixeladjacent to a red pixel (ST13). Next, a blue color filter is formed on atransmission CF portion as a part of a blue pixel adjacent to the greenpixel (ST14). After that, a red reflection CF is formed continuinglyfrom the transmission CF portion of the red pixel (ST15). Next, a greenreflection CF is formed continuingly from the transmission CF portion ofthe green pixel (ST16). Finally, a blue reflection CF is formedcontinuingly from the transmission CF portion of the blue pixel (ST17).From the above, RGB pixels comprising both of the transmission CFportion and the reflection CF portion are formed.

On the other hand, in the present invention, as shown in the flowchartin FIG. 2, the conventional coloring process can be halved. Note thatthe coloring order of red, green and blue can be changed in accordancewith characteristics of respective colors.

FIG. 6 illustrates a spectral transmittance of the transmission portionCF of the blue pixel in the conventional method. In FIG. 6, the abscissaindicates a wavelength and the ordinate indicates a transmittance. Thetransmission portion CF of the blue pixel in the conventional methodexhibits a peak of the transmittance at short of a wavelength of 500 nmas shown in FIG. 6.

FIG. 7 illustrates a spectral transmittance of the reflection portion CFof the blue pixel in the conventional method in the same way. In FIG. 7,the abscissa indicates a wavelength and the ordinate indicates atransmittance. Conventionally, different materials are used in thetransmission portion CF and the reflection portion CF, so the spectraltransmittance are also different. The spectral transmittance of thereflection portion CF has a broader spectral characteristics comparingwith that of the transmission portion CF and the transmittance risesover the whole visible wavelength range.

On the other hand, in the present invention, the spectral transmittanceof the color filter is basically identical in the transmission regionand the reflection region. By opening the CF windows on the reflectionregion, a light transmitted through the CF window reflects without beingcolored by the color of the color filter. An observer recognizes themost light reflected on the reflection portion of pixels and colored bythe color filter together with a color-free light as a part passedthrough the CF windows and, as a result, recognizes as a color, whereina coloring concentration is faded, which is similar to that of aconventional reflection type color filter.

Logically, the spectral transmittance in the case of further providingthe CF windows to the conventional transmission type CF can be givenfrom the following formula.T _(CF) =T _(W) ² *S+T _(R) ²*(1−S)

Here, “T_(CF)” indicates a transmittance after combining, “T_(W)”indicates a transmittance of the CF windows, “S” indicates an apertureratio of the CF windows and “T_(R)” indicates a transmittance of the CF.Also, the aperture ratio “S” of the CF windows can be given from (anarea of CF window)/(a CF area of one pixel).

FIG. 8 illustrates spectral transmittance characteristics of a colorfilter of the reflection region produced according to the presentinvention. Note that the spectral transmittance is obtained by asimulation based on the above formula and is a calculation result of thecase where a light transmits the color filter twice by assuming the caseof a reflection region. In FIG. 8, the abscissa indicates a wavelengthand the ordinate indicates transmittance.

Also, in FIG. 8, a curve “a” indicates a spectral transmittance when theaperture ratio of the CF windows is 15%. Similarly, a curve “b”indicates the case where the aperture ratio of the CF windows is 10%,and a curve “c” indicates the case where the aperture ratio of the CFwindows is 5%. Note that a curve “d” indicates a spectral transmittanceof a conventional transmission type CF. Here, the aperture ratio of theCF windows is important, and the total transmittance T_(CF) aftercombining can be adjusted by changing it.

To change the aperture ratio, a method of changing the number and a sizeof the CF windows can be applied. Namely, to optimize the apertureratio, a color filter having spectral characteristics close to those ofa color filter applied to a conventional reflection type can beobtained. Also, the color tone widely changes when the aperture ratiochanges by a few percents or so, so that high processing accuracy isrequired for forming the CF windows.

Also, total chromaticity x and y of the color filter provided with theCF windows can be obtained from the following formulas.

$X = {K*{\int_{380}^{780}{{T_{CF}(\lambda)}*{S(\lambda)}*{\overset{\_}{x}(\lambda)}\ {\mathbb{d}\lambda}}}}$$Y = {K*{\int_{380}^{780}{{T_{CF}(\lambda)}*{S(\lambda)}*{\overset{\_}{y}(\lambda)}*{\mathbb{d}\lambda}}}}$$Z = {K*{\int_{380}^{780}{{T_{CF}(\lambda)}*{S(\lambda)}*{\overset{\_}{z}(\lambda)}\ {\mathbb{d}\lambda}}}}$$K = \frac{100}{\int_{380}^{780}{{S(\lambda)}*{\overset{\_}{y}(\lambda)}\ {\mathbb{d}\lambda}}}$${x = \frac{X}{X + Y + Z}},{y = \frac{Y}{X + Y + Z}},{z = \frac{Z}{X + Y + Z}}$

Note that S(λ) indicates spectral intensity of a light source, x (λ), y(λ) and z (λ) are color matching functions based on the CIE1931.

As is clear from the above formulas, chromaticity depends on the T_(CF).The xy chromaticity diagram in FIG. 9 is a graph thereof. When theaperture ratio of the CF windows is increased from 5% to 15%, thechromaticity of the blue color filter moves to the center on the xyplane. By adjusting the aperture ratio of the CF windows, thechromaticity of the color filter can be optimally set.

FIGS. 10A to 10C are schematic views of the general configuration of ahybrid type liquid crystal display device.

In FIG. 10A to FIG. 10C, the reference number 10 indicates a first (CF)substrate and 20 indicates a second (TFT) substrate. The TFT substrate20 is formed signal lines 21, gate lines 22, pixel transistors 23,reflection electrodes 24 and transparent electrodes 25.

FIG. 10A shows the general configuration of the first (CF) substrate 10.A red pattern, a green pattern and a blue pattern are formed in a stripeshape on a transparent base made by a glass, etc. Furthermore, a blackpattern is formed to surround the RGB pattern. As explained above, thepatterns of respective colors can be formed by successively repeatingfilm forming of photosensitive coloring material and photolithography.

FIG. 10B shows three pixels of a liquid crystal display device. Aplurality of pixels are formed on the TFT substrate 20 side. Tocorresponding thereto, a red pattern, a green pattern, and a bluepattern in a stripe shape are formed on the CF substrate 10 side. Areflection electrode 24 composing a reflection portion and a transparentelectrode 25 composing the transmission portion are formed on respectivepixels on the TFT substrate 20. Furthermore, a pixel transistor 23 isformed to drive a pixel electrode composed of the reflection electrode24 and the transparent electrode 25. The pixel transistor 23 is a thinfilm transistor, wherein a gate electrode of the pixel transistor 23 isconnected to the gate line 22 and a source electrode is connected to thesignal line 21.

FIG. 10C is a further enlarged perspective view of one pixel. A colorfilter is formed on the CF substrate 10 so as to be corresponding topixels formed on the TFT substrate 20. In the general configuration, thereflection region CFR corresponding to the reflection electrode 24 andthe transmission region CFT corresponding to the transparent electrodeuse different color filter materials.

On the other hand, in the present invention, a common color filter isformed for the reflection region and the transmission region, and the CFwindows are provided on the reflection region. A specific example of theCF windows is shown in FIG. 11A to FIG. 11C. FIG. 11A shows theconfiguration on the TFT substrate 20 side, wherein the pixel PXL isdivided to a transmission portion T and the reflection portion R. A sizeof the pixel PXL is, for example, 100 μm×300 μm.

FIG. 11C is the configuration on the CF substrate 10 side producedaccording to the present invention, and one window CFW is formed in thereflection region. The CFW is formed inside the reflection region awayfrom the surrounding edges thereof by 2 μm or more. A size of the CFwindow is, for example, 60 μm×100 μm and the aperture ratio is set to20%.

FIG. 11B shows a reference example, wherein the window CFW is formed inthe same way as in FIG. 11C but is not formed in the reflection regionbut extending to the surrounding edges of the reflection region.

FIGS. 12A and 12B illustrate a disadvantage of the case of forming acolor filter of the reference example shown in 11B. The reference numberWDT11 in FIG. 12A indicates a width of the CF window affected bydeviation, and the reference number WDT12 in FIG. 12B indicates a widthof the original CF window.

As shown in FIG. 12A, when forming color filters, for example, in thecoloring order of R, G and B in the CF forming process, a green patternis aligned with respect to a red pattern by leaving a certain error.Similarly, a blue pattern is aligned with respect to the green patternby leaving a certain error in the same way. As a result, as shown inFIG. 12A, there arises the case that the CF window is blocked byadjacent CFs due to the alignment errors. In this case, a predeterminedaperture ratio of the CF windows cannot be maintained, and there arisesdeviation of color tone on the color filter on the reflection region.

To prevent such a problem, as shown in FIG. 11C, it is sufficient if theCF window is formed away from edges of the CF by leaving a distance ofat least an amount that the adjacent CFs are deviated due to thealignment errors. Normally, it is sufficient if the CF window is formedinside by leaving a distance of 2 μm or more from surrounding edges ofthe reflection region. More preferably, it is suitable to leave 3 μm ormore. Note that when alignment accuracy is improved, the limit of thedistance naturally becomes less.

FIG. 13 is the overall configuration of a liquid crystal display devicewherein CF windows are formed on the reflection region of the CFsubstrate as explained above. The reference number D10 in FIG. 13indicates a distance between the transparent electrode 25 on the TFT 1side and a CF window.

As shown in FIG. 13, the CF substrate 10 is assembled to be a liquidcrystal panel by being superposed with the TFT substrate 20. Thereflection electrode 24 on the TFT substrate 20 is formed by a lightreflecting film, and the transparent electrode 25 is formed by a lighttransmitting film. The both substrates 10 and 20 are superposed so thata pattern on the color filter on the CF substrate 10 superposes with apattern of the pixel electrode composed of the reflection electrode 24and the transparent electrode 25 on the TFT substrate 20. At this time,a CF window (CFW) is formed on the reflection region CFR on the CFsubstrate 10 side.

Accordingly, the CF window must not be superposed with the transparentelectrode portion on the TFT substrate 20 side. However, there actuallyarises an alignment error between the both substrates 10 and 20 due to amechanical error of a superposing apparatus. When such alignmentdeviation arises, a CF window having a faded color concentration isobserved through the transparent electrode, so that the display qualityis largely deteriorated. Thus, to prevent this, it is preferable to forma CF window away from the transparent electrode 25 by leaving a distancecaused by alignment deviation or more.

As a result, even if alignment deviation arises between the bothsubstrates, the transmission CF corresponds to the transparentelectrode, so that a color concentration does not deteriorate.Considering alignment accuracy between the both substrates, the distanceD10 between the CF window and edges of the transparent electrode 25 onthe TFT side is preferably 2 to 3 μm. Naturally, when alignment accuracyis improved, the limit of the distance can be made less.

Generally, an exposure apparatus for photolithography used in the CFprocess is called a proximity exposure apparatus, by which a parallellight is irradiated from the light source side to the mask. The exposureprocessing is performed in a state where mask and the substrate areclosely arranged by leaving certain constant distance so as not to toucheach other. The distance between the mask and the substrate at this timeis called an exposure gap and is a significant factor to determineexposure accuracy.

FIG. 14 is a schematic view of a patterning method of the color filter.In FIG. 14, the reference number 30 indicates a substrate, 31 indicatesa photomask, 32 indicates light block films and GP30 indicates theexposure gap.

As shown in FIG. 14, when the exposure gap GP30 is small, diffractionlight intensity depending on a pattern arrangement of the light blockfilm 32 of the photomask 31 becomes small. When the exposure gap GP30becomes large, the diffraction light intensity becomes large and adiffraction pattern gradually increases. Therefore, pattern formingfaithful to the light block film 32 pattern on the photomask 31 sidebecomes impossible.

Considering such a diffraction phenomena, when arranging a plurality ofCF windows adjacent to each other, it is important to arrange the CFwindows having a certain distance in advance. Due to this, a patternunevenness caused by diffraction can be prevented. In the illustratedexample, when the exposure gap GP30 is set to 150 μm, it is preferablethat a distance between CF windows is 10 μm or more, more preferably 20μm or more. When reducing the exposure gap GP30, the distance betweenthe CF windows can be also reduced.

Note that, in the example shown in FIG. 14, a CF window is formed byforming a light block film 32 on the photomask 31 and performingexposure processing. In this case, since a coloring layer of the colorfilter is completely removed from the CF window, the coloringconcentration becomes 0. Instead of this, and as shown in FIG. 19, CFwindows wherein the color filter on the CF window is left to a certainextent to have a lowered color concentration may be also used.Specifically, by creating a half exposure condition by using a lightblock film pattern in a slit shape, a film thickness of the coloringlayer of the CF window can be made thin.

Graphs in FIG. 15A and FIG. 15B show an exposure amount reaching to thesubstrate in the case where the exposure gap is set to 150 μm and awidth size of the light block film pattern is set to 20 μm. FIG. 15Ashows the case where the distance between CF windows is set to 6.5 μm.On the other hand, FIG. 15B shows the case where the distance between CFwindows is set to 15 μm. In FIG. 15A and FIG. 15B, the abscissaindicates a position on the substrate surface and the ordinate indicatesrelative intensity.

When the distance between the CF windows is 15 μm, a sufficient lightamount reaches between the CF windows and patterning faithful to thelight block film pattern becomes possible. On the other hand, when thedistance between the CF windows is 6.5 μm, a sufficient exposure lightdoes not reach between the CF windows due to diffraction. This meansthat size variation between the CF windows is easily caused.Furthermore, the exposure gap varies due to warps of the photomask orsubstrate surface. Even in such cases, a stable light amount can beobtained by separating adjacent CF windows by keeping a distance of atleast 10 μm, preferably 15 μm or more.

FIG. 16 is a schematic plan view of a specific example of the CF windowof the color filter. FIG. 16 illustrates a set of RGB three pixels,wherein sizes of CF windows are optimized for the respective CF windowsto obtain preferable color tone for color display. In the blue pixel,one CF window is provided, by which the aperture ratio of 5% is aimed.In the red pixel, two CF windows are provided, by which the apertureratio of 20% is aimed. Similarly, in the green pixel, two CF windows areprovided, by which the aperture ratio of 20% is aimed.

Not only by optimizing the number and size of the CF windows as above,but by devising an arrangement thereof a so-called moiré is preventedfrom arising. Namely, by setting different coordinates to be arranged ofCF windows for respective pixels, a moiré caused by a cyclicconfiguration is suppressed and the display quality is improved.Specifically, as shown in the figure, the CF windows are made not tohave the same distance and arrangement angles between respective RGBpixels.

When providing a plurality of CF windows, an arrangement of CF windowsof other color is made to have a different angle and distance from thoseof a CF window arrangement of the adjacent color. Due to this, colorunevenness due to the moiré phenomenon can be prevented.

Namely, in a color filter according to the present invention, whenarranging a plurality of windows respectively for pixel regions ofdifferent colors, arrangement directions of the plurality of windows aredifferent between pixel regions of different colors. Consequently, themoiré can be prevented. Also, when arranging one window in therespective pixel regions of different colors, the arrangementcoordinates of the respective windows are different between pixelregions of different colors. Consequently, the moiré can be prevented.

In the specific example in FIG. 16, a black mask in lattice is notformed between the RGB pixels, so that pixel regions of different colorsare directly next to each other without the black mask. In the case ofsuch a configuration, declining of the contrast can be prevented byforming CF windows inside the respective pixel regions. Assuming thatthe windows are formed not inside the pixel regions but on the framesalong the pixel regions, the CF windows are formed exactly at theposition of the black mask. In such a pattern, a reflection light isemitted as it is from the lattice CF windows, so that the black levelbecomes weak and the contrast declines. On the other hand, since the CFwindows are provided inside the pixel regions in the present invention,the contrast can be maintained even in the configuration without a blackmask.

FIG. 17 is a graph of the chromaticity of a reflection CF of the colorfilter shown in FIG. 16. In the illustrated xy chromaticity diagram, theCF chromaticity by the present invention is indicated by a “□” mark andthe CF chromaticity by the conventional method is indicated by a “Δ”mark. In the conventional method, a color filter adjusted to areflection region is used. On the other hand, in the present invention,a condition close to the chromaticity of the reflection CF is obtainedby providing CF windows to an originally transmission type color filter.As is clear from the graph, the chromaticity of the reflection CF by thepresent invention is almost the same as that of the reflection CF by theconventional method. As is clear from the FIG. 17, according to thepresent invention, it became possible to maintain complementary for thechromaticity while realizing a reduction of processes and reduction ofcosts.

FIG. 18 is a schematic view of other aspect of the present invention.

As explained above, a liquid crystal panel comprises a CF substrate 10and a TFT substrate arranged facing to each other over a liquid crystallayer. As shown in the figure, the TFT substrate is formed pixels PXLarranged in matrix, and each pixel is formed a reflection portion R toreflect an outside light and a transmission portion T to transmit alight. On the other hand, the CF substrate is formed a color filter forcoloring each of the pixels PXL to be different colors (red, green andblue).

As is clear from FIG. 18, the arrangement coordinates of thetransmission portion T in a pixel differ between pixels PXL colored tobe different colors. By applying a random arrangement configuration asabove, a regular pattern is removed as much as possible and a moiré canbe suppressed.

INDUSTRIAL APPLICABILITY

In a liquid crystal display device of the present invention, atransmission type color filter and a reflection type color filter aresimultaneously formed, so that the production process can be reduced to½ of the conventional method and a reduction of costs can be realized.Therefore, the liquid crystal display device can be applied, forexample, to a so-called hybrid type liquid crystal display devicewherein both of a reflection portion and a transmission portion areprovided in each pixel.

1. A liquid crystal display device comprising: a first substrate and asecond substrate facing each other with a liquid crystal there between,said first substrate is formed having pixels arranged in matrix, andeach pixel of a plurality of pixels has a reflection portion to reflectan outside light and a transmission portion to transmit light; and saidsecond substrate is formed with a plurality of different color filters,each corresponding to respective pixels; further comprising one or morecolor adjusting windows located at regions of the color filtercorresponding to the reflection regions of the plurality of pixels, thecolor adjusting windows having a coloring concentration of more thanzero and less than that of remaining portions of the color filters,wherein the color adjusting windows are substantially 30 μm or less inat least one of a width and a length direction.
 2. The liquid crystaldisplay device according to claim 1, wherein the color adjusting windowsare substantially 30 μm or less in both a width and a length direction.3. The liquid crystal display device according to claim 1, wherein thenumber of color adjusting windows formed in the color filtercorresponding to each reflection region is varied across the colorfilter.
 4. The liquid crystal display device according to claim 3,wherein there is at least one color adjusting window formed in everycolor filter region corresponding to each pixel reflection portion. 5.The liquid crystal display device according to claim 1, wherein thetotal area of the color adjusting windows formed in the color filtercorresponding to each reflection region is varied across the colorfilter.
 6. The liquid crystal display device according to claim 5,wherein there is at least one color adjusting window formed in everycolor filter region corresponding to each pixel reflection portion. 7.The liquid crystal display device according to claim 1, wherein no coloradjusting window is formed within a distance of 2 μm from an edge of aregion corresponding to said reflection regions.